The present invention relates to the field of communications, and, more particularly, to a coaxial cable jumper assembly and related methods.
Coaxial cables are widely used to carry high frequency electrical signals. Coaxial cables enjoy a relatively high bandwidth, low signal losses, are mechanically robust, and are relatively low cost. A coaxial cable typically includes an elongate inner conductor, a tubular outer conductor, and dielectric separating the inner and outer conductors. For example, the dielectric may be a plastic foam material. An outer insulating jacket may also be applied to surround the outer conductor.
One particularly advantageous use of coaxial cable is for connecting electronics at a cellular or wireless base station to an antenna mounted at the top of a nearby antenna tower. For example, the transmitter and receiver located in an equipment shelter may be coupled via coaxial cables to antennas carried by the antenna tower. A typical installation includes a relatively large diameter main coaxial cable extending between the equipment shelter and the top of the antenna tower to thereby reduce signal losses. For example, CommScope, Inc. of Hickory, N.C. and the assignee of the present invention offers its CellReach(copyright) coaxial cable for such applications.
Each end of the main coaxial cable may be coupled to a smaller diameter, and relatively short, coaxial cable jumper assembly. The coaxial cable jumper assembly includes a length of coaxial cable with connectors attached to the opposing ends. The cable of the jumper cable assembly is typically of a smaller diameter than the main coaxial cable to provide a smaller cross-section, greater flexibility and facilitate routing at the equipment shelter, and also at the top of the antenna tower, for example. Connectors are typically coupled to each end of the jumper coaxial cable to form the coaxial cable jumper assembly.
A coaxial cable is typically manufactured in a continuous fashion wherein an inner conductor or wire and is advanced along a path through an extruder which extrudes a dielectric foam around the inner conductor. Downstream from the extruder are a series of cooling tanks to cool and solidify the dielectric foam. The outer conductor may be applied as a metallic tape formed into a tube around the dielectric layer. The plastic insulating jacket may be extruded downstream from application of the outer conductor.
The connectors for the jumper cable assembly can be installed onto the ends of the coaxial cable at the cable manufacturing plant and/or in the field. Connectors are available in two main categoriesxe2x80x94mechanical-type connectors which are configured for mechanical installation onto the end of the jumper coaxial cable, and solder-type connectors which are configured to be coupled by soldering. Unfortunately, the mechanical-type connector is relatively complicated, includes many parts, and, therefore, is relatively expensive. Solder-type connectors may be less expensive because of fewer parts. For example, U.S. Pat. No. 5,802,710 to Bufanda et al. discloses a solder-type connector which uses a solder perform wrapped around an annularly corrugated outer conductor of the coaxial cable. The connector body is placed over the solder perform and then heated to solder the connector to the end of the cable.
Unfortunately, not all materials used in connectors and/or coaxial cables are readily suited to soldering. Aluminum is a highly desirable material and is often used for the outer conductor of a jumper coaxial cable. Unfortunately, aluminum does not readily accept solder, and, therefore, more expensive mechanical-type connectors have typically been used in combination with a jumper coaxial cable having an aluminum outer conductor.
In view of the foregoing background, it is therefore an object of the present invention to provide a coaxial cable jumper assembly that is rugged and readily manufactured, that includes aluminum as the outer conductor material, and which includes at least one solder-type connector.
The connectors for the jumper cable assembly can be installed onto the ends of the coaxial cable at the cable manufacturing plant and/or in the field. Connectors are available in two main categories - mechanical-type connectors which are configured for mechanical installation onto the end of the jumper coaxial cable, and solder-type connectors which are configured to be coupled by soldering. Unfortunately, the mechanical-type connector is relatively complicated, includes many parts, and, therefore, is relatively expensive. Solder-type connectors may be less expensive because of fewer parts. For example, U.S. Pat. No. 5,802,710 to Bufanda et al. discloses a solder-type connector which uses a solder preform wrapped around an annularly corrugated outer conductor of the coaxial cable. The connector body is placed over the solder perform and then heated to solder the connector to the end of the cable.
The outer conductor may have a continuous, non-braided, tubular shape. The tin layer may extend continuously along an entire length of the outer conductor, and be on a radially-outer surface of the aluminum layer, for example. The tin layer may be readily formed by plating during manufacturing of the jumper coaxial cable.
The jumper cable assembly may include first and second connectors on opposing first and second ends of the jumper coaxial cable. The jumper coaxial cable may have characteristics to be shape-retaining when formed into a shape having at least one bend therein. This shape-retaining quality may be especially advantageous when routing the jumper assembly to rack-mounted electronic equipment, such as a transmitter or receiver.
The inner conductor may comprise an aluminum rod with a copper layer thereon. The connector may further comprise a connector contact coupled to the inner conductor. The dielectric layer may include plastic, such as a plastic foam, for example. In addition, the jumper coaxial cable may have a diameter in a range of about xe2x85x9 to 2 inches.
Another aspect of the invention relates to a coaxial cable system including a main coaxial cable and a coaxial cable jumper assembly, including the tin-plated outer conductor, and connected to one or both ends of the main cable. The main coaxial cable may have a larger diameter than the coaxial cable of the jumper assembly to thereby reduce signal attenuation. The smaller cable of the jumper assembly may be more flexible and shape retaining which would allow tighter bends required in many routing applications.
Yet another aspect of the invention is directed to a method for making the coaxial cable jumper assembly as described above. The method may include forming a tin layer on an aluminum outer conductor of a jumper coaxial cable comprising an inner conductor and a dielectric layer between the inner and outer conductors; and soldering at least one connector to the tin layer adjacent at least one respective end of the jumper coaxial cable. The tin layer may be a tin alloy, such as a tin/lead alloy, for example, as noted above. The outer conductor may have a continuous, non-braided, tubular shape, and the tin layer may be formed by plating.